Today, Warren Buffett has a net worth of $75 billion. It took him 26 years from the time he became a millionaire to the time he made his first billion. Bill Gates has $90 billion today. It took him just five years to go from his first million to his first billion. That's pretty fast, but it has nothing on the billionaire with the fastest transition from millionaire to billionaire. That distinction goes to Facebook founder Mark Zuckerberg, who took just one year to make the leap from millionaire to billionaire.

Mark Zuckerberg debuted on the list of the world's billionaires in 2008. He was 23 years old. By 2009, he was off the list due to a drop in Facebook's valuation. The following year he was back in the billionaire's club and he's never looked back

Not surprisingly, founding a big tech company is one of the fastest ways to become a billionaire. It took Amazon's Jeff Bezos just two years to jump from millionaire to billionaire. Google co-founders Larry Page and Sergey Brin took five years to get there, just like Microsoft's Bill Gates.

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Below is a list of 25 of the richest billionaires in the world and how long it took them to make the leap from millionaire to billionaire.

Amy Lamare is a Los Angeles based writer covering business, technology, entertainment, philanthropy, and pop culture. She spent 8 1/2 years covering the entertainment industry for www.hsx.com. She has written for Los Angeles Magazine, Your Tango, Thinknum Media, and various airline magazines. Follow her on Facebook. Amy's favorite self-made billionaire is Sara Blakely.